In an LTE (Long Term Evolution) mobile communication system in 3GPP, a mobile station UE receives, as a setting related to a measurement, “MeasConfig” from a radio base station eNB. The “MeasConfig” may include one or a plurality of “ReportConfig”, “MeasObject”, or “MeasId”.
The “ReportConfig” is used to set a condition under which a measurement report “MeasReport” from the mobile station UE to the radio base station eNB is triggered.
For example, in a condition defined in “Event A3”, when a measurement result of a neighboring cell is higher than an offset than a measurement result of a current serving cell, the “MeasReport” is triggered.
Furthermore, in a condition defined in “Event A4”, when a measurement result of a neighboring cell is higher than a predetermined threshold value, the “MeasReport” is triggered.
The offset, the threshold value, the type of a condition, etc., are set in the “ReportConfig”.
Furthermore, the “MeasObject” is used to set RAT or a frequency that the mobile station UE should measure. The “MeasObject” includes an offset value that should be applied to a measurement result for each cell, a list of cells that should be excluded from a cell to be measured, and the like.
The “MeasId” is used to link a single “ReportConfig” to a single “MeasObject”, and the mobile station UE measures only “MeasObject” in which the “MeasId” has been set, and transmits the measurement report “MeasReport” to the radio base station eNB only when satisfying a condition of the “ReportConfig” linked to the “MeasObject” by the “MeasId”.
The mobile station UE is to report the measurement results of a cell on the “MeasObject”, in which the condition is satisfied, and a current serving cell, through the “MeasReport”.
In the 3GPP, in an LTE-Advanced mobile communication system, when a mobile station UE performs a handover during a CA (Carrier Aggregation) communication, it is not determined which one of: a radio base station S-eNB managing a handover source cell; and a radio base station T-eNB managing a handover destination cell, selects PCC (Primary Component Carrier) of the mobile station UE in the handover destination cell.
On this point, the following two points have been proposed in Non Patent Literature 1.
(1) A radio base station eNB#A managing the handover source cell selects the PCC of the mobile station UE in the handover destination cell.
(2) In order for a radio base station eNB#B managing the handover destination cell to select SCC (Secondary Component Carrier) of the mobile station UE in the handover destination cell, the radio base station eNB#A managing the handover source cell transfers a measurement result of the handover destination cell on each CC (Component Carrier) to the radio base station eNB#B managing the handover destination cell.
For example, according to Non Patent Literature 1, in an example of FIG. 9, when a mobile station UE covering “Pcell=A11” and “Scell=A21” is handed over to a cell subordinate to the radio base station eNB#B, the radio base station eNB#A is configured to transfer measurement results of a cell B13 and a cell B23 to the radio base station eNB#B.
Furthermore, in the example of FIG. 9, it is assumed that cells A11, A12, A13, B11, B12, B13, C11, C12, and C13 are cells on CC#1, and cells A21, A22, A23, B21, B22, B23, C21, C22, and C23 are cells on CC#2 having a carrier frequency different from that of the CC#1.